Apparatus for the sterilization of liquids without the use of heat or chemicals



April 28, 1942.

LIQUIDS WITH@ THE USE OF HEAT OR CHEMICALS Filed March l5, 1940 APPARATUS FOR THE Patented Apr. 28, 1942 i vnorm APPARATUS FOR THE STERILIZATION OF LIQUIDS WITHOUT THE USE OF HEAT OR CHEMICALS Hubert S. Ogden, Los Angeles, Calif., assignor to Robert M. Vaillancourt, Pasadena, Calif.

Application March 13, 1940, Serial No. 323,772

(Cl. Z50-49) 4 Claims.

The object of my process is to sterilize liquids, especially those that are subject to human consumption. Such liquids, in their raw state, have a large bacterial content commonly designated as a plate count. They furthermore provide, if not sterilized by some means, a natural incubating media. Sterilization or" liquids, especially those used for human consumption, is usually accomplishedrby raising the temperature of the liquid to a point Where the bacteria is destroyed. This process on a commercial scale is unsatisfactory for the reason that absolute control of the plate count cannot be consistently maintained unless excessive temperatures are used. An absolute negative plate count cannot be obtained without destroying in part the vitamin content of the liquid. Calcium in the liquid when subjected to the heatof sterilization becomes dicult to assimilate by the human digestive system. The flavor of the liquid is affected. It is usually desirable to refrigerate the liquid for storage, thus sterilization by heating affects the economy of the process.

A further object of my process is to sterilize liquids without the application of heat or chemicals. Another purpose of my process is to provide a means for the cold sterilization of liquids that is readily controlled to the end that the desired plate count can be absolutely maintained. Another purpose of my process is to sterilize liquids without contaminating the liquid by ozone or other chemical odors. Another purpose of my process is to provide a meansfor the eiicient distribution of the sterilizing agent. Another purpose of my process is to sterilize liquids in such a manner that the flow of the liquids through the apparatus of my process is at a definite and predetermined rate, the rate of llow being governed by the density of the liquids, the intensity of the sterilizing agent and the desired final plate count, each being mathematically dependent upon the other, thereby reducing the element of error commonly caused by faulty judgment of the operator.

I have conducted numerous experiments with my process and apparatus, using water, milk, raw fruit and raw vegetable juices, With equally satisfactory results. For the purpose of this specication I have chosen to demonstrate my process by referring to milk as the liquid to be sterilized. However, it is not to be construed that milk is the only liquid my process will sterilize. Any liquid can be substituted for the milk referred to in the specication.

Briey, my process consists of forming a film of the liquid to be sterilized on a moving surface and directing ultra violet rays through the film for a period of time that may be determined by the desired plate count, by the intensity of the rays, by the density of the liquid or-'by all three of the foregoing factors. l l

I have tried several methods of creating a lm of the liquid to be sterilized but have found that the most satisfactory results are obtained if the liquid is passed through the apparatus described 4in the accompanying drawing. Like characters will be used to denote like and corresponding parts throughout the several views.

Figure 1 is a side view of the apparatus used in my process and is partly cut away.

Figure v2 is a section taken at random through the iram'e to show one method of creating a gas tight seal. l

Figure 3 is a more detailed view of a portion of the apparatus showing the method of transferring the liquid between the cylinders and the shape of the foam eliminating pans.

Figure 4 is a partial view of the auxiliary lm regulating means.

Figure 5 is one method of passing the scraper supporting shaft through the gas tight enclosing hood.

Referring more particularly to the drawing I0 is the supporting frame, II is a gas tight enclosing hood sealed against I2 a member of the supporting frame by means of sealing material I3 and wing nut I4. Supported on member I2 is a half bearing I5 in which is journalled shaft I6 of closed cylinder Il. Within the gas tight enclosing hood II and supported thereby are semicylindrical reflectors I8 which in turn support violet ray tubes I9-I9, Violet ray tubes III-I9 are connected through the usual high tension transformers, not shown, to a source of electric current. Passing through the gas tight enclosing hood II and cylindrical reflectors I8 and entering the space encompassed by cylindrical reflectors I8 are gas supply lines 20. Gas supply lines 20 are in turn connected to a source of inert gases. I have chosen to show a carbon dioxide generator 2| as the source of the inert gas but other inert gases such as helium, argon, Freon or nitrogen may be used. Sealed against and supported by member I2 of frame IU are pans 22. 23 is the cylinder rotating means. In this instance I chose to show the cylinder rotating means as a V belt and pulley drive, however, chain, worm and pinion, gear or other drives may be used. l23' is the connecting V belt. 24 is a variable speed device of the ex..

panding sheave type, however, other variable speed means may be used. is a V belt from the variable speed device to the cylinder rotating means 23. 26 is a V belt from the variable speed device to the driving motor 21. 28 is a direct reading tachometer mounted on the supporting frame IU adjacent tov the control 50 of the variable speed device 24. 29 vis a frame fixed to supporting frame In adjacent to tachometer 28. 30 is a chart mounted on frame 29. 3| is a liquid level regulating means here shown as the floating ball type. 32 is an electricmotor mounted on supply tank 33 and connected to agitator shaft and paddles 34 through bevel gear 35. 3B,

in discharge line 39.

45) is a trap In Voperation supply tank`v 33, which may be i located at any point higher than the desired liquid level in initial pan 22, isfilled through funnel 35 with the liquid to be sterilized, in this instance milk. Motor 3 2 is set in motion, revolving agitator paddle 34. This produces a uniform density of the liquid. The liquid passes through supplyline 3 1 forminga trap at 38 and then enters initial lpan 22, rising therein until the surface of the liquid is in contact with closed cylinder I 1. Liquid level device 3.! is adjusted to maintain thisA level. Motor 21 is, started, rotatine through, the variable speeddevce 24 and drives 23, cylinder I1-,.I1, clockwise as4 viewed. The arrows K-K headin the direction of rotation. Some of the liquid` in `pan 22adheres to the surface of cylinder I1. As the liquid adhering to cylinder I1 tends to move away and upward from, the Surface of the. main b odv 0f the liquid it is placedin tension. As the adhesion to the surface of the cylinder is greater than the cohesion of the liquid, the liquid tends, to break away from its main body and remain on the surface of the cylinder in a thin The thin filml of liquid is carriedvupward and through a bombardment of ultrav violet rays from tubes I9-I9 that have been electrically excited. 'Ihe liquid continues Athrough the range of the ultra violetray bombardment on the surfaceof cylinder :I1 until it reaches` position A lwhere it is removed from cylinder I1 by a closelyiitted scrapf er 4I. Scraper 4l is held against cylinder I1 by the action of weight 42 4through shaft 42' which is fixed to scraper 4I by means of lshaft 43. Scraper 4I is supported on frame member I2 by means of shaft 43 and pins 44-44. The liquid removed from cylinder I1 by scraper` 4 I flows down the inclined surface 4I of scraper 4I until it reached gap B. Gap, B4 is a small space between the lower end of scraper-IHI and surface C of inclined portion 45,4 of, intermediate pans 22-22. Gap B is justsufliciently large to permit a free movement-of scraperl 4I. The liquid in f loyvingrfrom` scraper 4I, to pan 22fby meansr quent violet ray bombardmentY a manner sirnilar to that already described for the Ainitial cylinder,` inasmuch-as Iexperiment has proven that the sterilizing effect'otultra violet ray bom-l 38 33 is the discliargev bardment is as effective as the intensity of the ray, the depth of the liquid or the time that the liquid is exposed to the rays, by multiplying the number of cylinders and the corresponding violet ray tubes any degree of sterilization will be attained. As the length of exposure also determines the degree of sterility, andas the length of exposure can be governed by the speed 'of rotation of cylinders I1-I1, tachometer 28 is used to inrdicate the speed of rotation and chart 30 to indicate thel degree of sterility at any given speed. 'Ihus the rate of rotation or degree of sterility is regulatedbyv means of the variable speed device. For example, the chart can be made to readU interms of revolution per minute as one ordinate and plate count as the other ordinate, or, pintsper minute as one ordinate and plate countl theother ordinate. For instance, milk with a desired final plate count of 1,100 would be the equivalent of operating the apparatus at 40 revolutionsper minute or discharging ll/zeallons per minute, or for a desired final plate count of 5,00 wouldbeitheequivalent of 30 revolutions per minute or 1 gallon per minute, ,or` for adef sired final plate count of 3 00 would be the equivalent of 25 revolutions per minute or 3 pints per minute. Thus it can be seen that a chart can be made to enablea direct settinglof the speed of the apparatus relative to the final plate count and once that setting ismade no further adjustments. are necessary.

Inasrnuch as the, intensity of the ultra violet rays vary inverselvzas the. square of the distance from the source to theiobjective I have found through experiment that, the semicylindrically shaped reflector and tube support I3 is most efiicient,1 as bythis arrangement the center lines of all the tubes l S-IS areequi-distant from the surface of the closed Cylinder I1.

After the liquid to be sterilized has passed over the several cylinders I1I1 and hasbeen removed from the final cylinder I1 by the nal scraper 4I ,into final pan 22, it is4 discharged therefrom brmeans, @discharge 1111erA 39. Trap 40 formed by the discharging vliquid is beneficial in retaining the inertgas within the apparatus.

5 l-5I are particles of the .liquid as they pass from one cylinder to another,V and are to be considered for the sakevof discussion as separated particles of the liquid forming by close adhesion to eachother a, continuous film. I have found by experiment that as, theA liquid is carried upwardon the surface. E of cylinderw|1 some ofA thel particles `of 4the, liquid break away from the main mass or nlmk and travel downward over the film` back to the surfaceF of the liquid in pan 22. Arrow I-I indicates the direction of the returningparticlesof the liquid. These returning particles marked .55, have a turbulence producing action .which further tends to improve the penetration Vof ,the ultraviolet ray into` the liquid. Because` of this return` flow actionrof some of the particles, the thickness of the lin of the liquid on the surface of cylinder I1 can be readily controlled byl varying'A the. rate of frotation ofY cylinder I1. An auxiliary film thickness adjustment plate is mounted on screw adjusting means 6I and set against .the upward moving `side of cylinder l1. This provides anY additional means of controlling the thickness of the liquid film. It is, useful in such instances where aheavierpr. more viscous-liquidmay be introduced into the apparatus for sterilization. Advancing or withdrawing adjusting',l plate 6.0. kiniiu;`

ences the thickness of the lm of the liquid before it passes through the violet ray bombardment by increasing or decreasing gap G.

I have found that by surrounding the violet ray tubes with an inert gas and driving such free air as may be in the apparatus from under the cylindrical reectors I8 I can prevent the formation of ozone which contaminates milk to the taste.

In reducing the invention to practice I reserve the right to make such modifications in method and design as may lay within the scope of what I claim.

What I claim is:

1. In an apparatus for the sterilization of liquids without the use of heat or chemicals, wherein a liquid is passed through an apparatus comprising a source of ultra violet r-ays the said rays being directed to the upper peripheral surface of a closed cy1inder,the lower peripheral surface of the cylinder held in contact with the liquid, a pan holding the liquid beneath the cylinder, to the end that foaming be eliminated, the said pan having a gently sloping portion immediately beneath the point where liquid is admitted to the pan and a gently curved surface leading from the lower end of the gently sloping portion to the bottom of the aforesaid pan.

2. In an apparatus for the sterilization of liquids by means of ultra-violet rays, a semicylindrical hood encompassing a cylinder, the said hood supporting a multiplicity of ultra-violet ray tubes, the said tubes so mounted within the said hood that the longitudinal axis of the said tubes be parallel to the axis of the said cylinder, and as close to the cylinder as is practical, the said hood so shaped as to parallel the cylinder, the said tubes so arranged as to follow the y outline of the cylinder, to the end that the major portion of the surfaceof the cylinder simultaneously receive a uniform exposure of the ultraviolet rays.

3. In -an apparatus for the sterilization of liquids by means of ultra-violet rays, a cylinder, a hood encompassing said cylinder, a multiplicity of ultra-violet ray tubes mounted within said hood so that the longitudinal axis of said tubes parallels the longitudinal axis of said cylinder, and as close to the cylinder as practical, said hood paralleling said cylinder, the said tubes so arranged as to closely follow the outline of the cylinder, to the end that the exposed surface of the cylinder simultaneously receives a uniform exposure to the ultra-violet rays.

4. In an apparatus for the sterilization of liquids by means of ultra-violet rays, a cylinder, a curved reiiecting surface having its axis coincident with the axis of said cylinder, a multiplicity of ultra-violet ray tubes mounted between said reflecting surface and the surface of said cylinder to be irradiated so that the longitudinal axis of said tubes parallels the longitudinal axis of said cylinder, said tubes so arranged as to follow closely the curvature of said cylinder, to the end that said surf-ace of the cylinder simultaneously receives a uniform exposure to the ultraviolet rays.

` HUBERT S. OGDEN. 

